PurposeTo evaluate in a prospective study the possibility of visualization and diagnostic assessment of the recurrent motor branch RMB of the median nerve with high-resolution ultrasound HRUS.

Materials and methodsHRUS with high-frequency probes 18–22 MhZ was used to locate the RMB in eight fresh cadaveric hands. To verify correct identification, ink-marking and consecutive dissection were performed. Measurement of the RMB maximum transverse-diameter, an evaluation of the origin from the median nerve and its course in relation to the transverse carpal ligament, was performed in both hands of ten healthy volunteers n = 20. Cases referred for HRUS examinations for suspected RMB lesions were also assessed.

ResultsThe RMB was clearly visible in all anatomical specimens and all volunteers. Dissection confirmed HRUS findings in all anatomical specimens. Mean RMB diameter in volunteers was 0.7 mm ± 0.1 range, 0.6–1. The RMB originated from the radial aspect in 11 55%, central aspect in eight 40% and ulnar aspect in one 5% hand. Nineteen 95% extraligamentous courses and one 5% subligamentous course were detected. Three patients with visible RMB abnormalities on HRUS were identified.

ConclusionHRUS is able to reliably visualize the RMB, its variations and pathologies.